/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.vfs.util;

import java.net.MalformedURLException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;

import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystem;
import org.apache.commons.vfs.FileSystemException;
import org.apache.commons.vfs.impl.DecoratedFileObject;
import org.apache.commons.vfs.provider.AbstractFileObject;
import org.apache.commons.vfs.provider.AbstractFileSystem;
import org.apache.commons.vfs.provider.DefaultURLStreamHandler;
import org.apache.commons.vfs.provider.UriParser;

/**
 * Stuff to get some strange things from an FileObject.
 *
 * @author <a href="mailto:imario@apache.org">Mario Ivankovits</a>
 * @version $Revision: 804886 $ $Date: 2009-08-17 09:38:49 +0200 (Lun, 17 Ago 2009) $
 */
public final class FileObjectUtils
{
    private FileObjectUtils()
    {
    }

    /**
     * Get access to the base object even if decorated.
     * @param fileObject The FileObject.
     * @return The decorated FileObject or null.
     * @throws FileSystemException if an error occurs.
     */
    public static AbstractFileObject getAbstractFileObject(final FileObject fileObject) throws FileSystemException
    {
        Object searchObject = fileObject;
        while (searchObject instanceof DecoratedFileObject)
        {
            searchObject = ((DecoratedFileObject) searchObject).getDecoratedFileObject();
        }
        if (searchObject instanceof AbstractFileObject)
        {
            return (AbstractFileObject) searchObject;
        }
        if (searchObject == null)
        {
            return null;
        }

        throw new FileSystemException("vfs.util/find-abstract-file-object.error",
                fileObject == null ? "null" : fileObject.getClass().getName());
    }

    /**
     * Check if the given FileObject is instance of given class argument.
     * @param fileObject The FileObject.
     * @param wantedClass The Class to check.
     * @return true if fileObject is an instance of the specified Class.
     * @throws FileSystemException if an error occurs.
     */
    public static boolean isInstanceOf(final FileObject fileObject, final Class wantedClass) throws FileSystemException
    {
        Object searchObject = fileObject;
        while (searchObject instanceof DecoratedFileObject)
        {
            if (wantedClass.isInstance(searchObject))
            {
                return true;
            }

            searchObject = ((DecoratedFileObject) searchObject).getDecoratedFileObject();
        }

        if (wantedClass.isInstance(searchObject))
        {
            return true;
        }

        return false;
    }
    
    /**
     * Returns a URL representation of the file.
     * @return The URL representation of the file.
     * @throws FileSystemException if an error occurs.
     */
    public static URL toURL( final FileObject fo ) throws FileSystemException
    {
    	final FileSystem fs = fo.getFileSystem();
    	
    	if( !(fs instanceof AbstractFileSystem)) {
    		throw new IllegalArgumentException( "fs is not valid!");
    	}
    	
        final StringBuffer buf = new StringBuffer();
        try
        {
            return  AccessController.doPrivileged(new PrivilegedExceptionAction<URL>()
            {
                public URL run() throws MalformedURLException
                {
                    return new URL(UriParser.extractScheme(fo.getName().getURI(), buf), "", -1,
                        buf.toString(), new DefaultURLStreamHandler( ((AbstractFileSystem)fs).getContext(), fs.getFileSystemOptions()));
                    
                    
                }
            });
        }
        catch (final PrivilegedActionException e)
        {
            throw new FileSystemException("vfs.provider/get-url.error", fo.getName(), e.getException());
        }
    }

}
